1. Field of the Invention
The present invention relates to a valve assembly of a reciprocal compressor, and more particularly to a valve assembly, installed on a cylinder head of a compressor for controlling discharge operation of refrigerant compressed in a cylinder.
2. Description of the Related Art
A freezing system such as a refrigerator has a compressor for compressing refrigerant. FIG. 1 illustrates a hermetic reciprocal compressor as one example of the compressor.
The compressor 1 has a casing 3 having a sealed inner space defined therein, a cylinder device 21 for compressing the refrigerant, and a driving motor 11 for driving the cylinder device 21.
In the casing 3 are formed a suction pipe 5 for drawing in gaseous refrigerant, a discharge pipe (not shown) for discharging refrigerant compressed by the compressor 1, and an electric terminal 9 for supplying electrical power to the compressor 1. The driving motor 11 has a stator 13, a rotor 15, and a shaft 19 rotated by the rotor 15. When the power is supplied through the electric terminal 9, the shaft 19 is rotated by the driving motor 11. The shaft 19 has an eccentric shaft 20 at a lower part thereof.
The cylinder device 21 comprises a cylinder body 23 having a cylinder chamber 23a defined therein, a cylinder head 65 installed on the cylinder body 23, a piston 25 reciprocating in the cylinder chamber 23a, and a connecting rod 27 connecting the piston 25 with the eccentric shaft 20. The eccentric shaft 20 and the connecting rod 27 convert a rotational movement of the shaft 19 into a reciprocating motion of the piston 25.
One side of the cylinder body 23 is open, and the cylinder head 65 is disposed to seal the open side. A valve assembly 30 having a valve plate 31 and a reed valve 61 is disposed between the cylinder body 23 and the cylinder head 65. A discharge hole 31b for discharging the refrigerant from the cylinder chamber 23a and a suction hole 31a for drawing the refrigerant into the cylinder chamber 23a are formed at the valve plate 31. The refrigerant, drawn from the outside through the suction pipe 5, is drawn into the cylinder chamber 23a through the suction hole 31a, and compressed in the cylinder chamber 23a by the reciprocal motion of the piston 25, and is discharged to the discharge pipe (not shown) through the discharge hole 31b. 
FIG. 2 is a partial enlarged view of FIG. 1, showing the valve assembly 30 disposed between the cylinder body 23 and the cylinder head 65. The valve assembly 30 comprises the valve plate 31 having the suction hole 31a (not shown in FIG. 2) and the discharge hole 31b as described above, the reed valve 61, disposed at the valve plate 31, for opening/closing the discharge hole 31b, a stopper 71 disposed above the reed valve 61, and a keeper 73 disposed above the stopper 71.
The keeper 73 is secured to the valve plate 31 by a settling bolt 75, and the reed valve 61 and the stopper 71 are secured to the valve plate 31 by the keeper 73. When the refrigerant in the cylinder 23a is discharged through the discharge hole 31b, the reed valve 61 is bent upwardly by the discharge force of the refrigerant. In such as situation, the stopper 71 gives a resistant force against the upwardly bending force of the reed valve 61. The keeper 73 limits deformation range of the stopper 71, when the stopper 71 is deformed by the bending force of the reed valve 61. Due to the function of the keeper 73, the deformation of the reed valve 61 and the stopper 71 is maintained without any changes, and the operation of the reed valve 61 and the stopper 71 is performed with stability, even though there is a constant repetition of opening/closing operations of the reed valve 61.
However, in such a conventional valve assembly 30 with the above construction, the location of the stopper 71 and the keeper 73 is fixed at one place, so there is a disadvantage that the reed valve 61 cannot operate actively, when discharge pressure of the refrigerant is high. In other words, when the discharge pressure of the refrigerant becomes abnormally high; the bending deformation force for opening the discharge hole 31b of the reed valve 61 also becomes abnormally great. Even in this case, since the location of the stopper 71 limited by the keeper 73 and the resistant force given by the stopper 61 are not changed, pressure in the cylinder chamber 23a increases because the opening degree of the discharge hole 31b is limited. Due to the increase of the pressure, the refrigerant cannot be discharged actively, and also compressing efficiency of the compressor 1 is decreased. Moreover, as a colliding force between the reed valve 61 and the stopper 71 increases, noise generated thereby also increases, and there is a possibility that the reed valve 61 and the stopper 71 are broken.
The present invention has been made to overcome the above-mentioned problems of the related art. Accordingly, it is an object of the present invention to provide a valve assembly of a reciprocal compressor capable of controlling opening degree of a reed valve by controlling bending deformation degree of the reed valve and a discharge hole according to increase and decrease of discharge pressure.
The above object of the present invention is accomplished by providing a valve assembly including a valve plate disposed between a cylinder body and a cylinder head and having a refrigerant discharge hole; a reed valve for sealing and opening the refrigerant discharge hole; a first stopper for resisting against a bending deformation force of the reed valve bent by a discharge force of refrigerant while the refrigerant is discharged through the refrigerant discharge hole; at least one second stopper for resisting against the bending deformation force of the first stopper by the reed valve; and a keeper for limiting degree of bending of the second stopper caused by the first stopper.
A controlling means for controlling the biggest bending degree of the second stopper is disposed at some part of the keeper. The controlling means can be a spring inserted between the second stopper and the keeper. Moreover, it can be a bolt settled at the keeper and connected with the second stopper bent by the first stopper, and distance between the second stopper and the bolt is controlled in accordance with the settling degree.
According to another preferred embodiment of the present invention, the valve assembly includes a valve plate disposed between a cylinder body and a cylinder head and having a refrigerant discharge hole; a reed valve for opening/closing the refrigerant discharge hole; a stopper for resisting against bending force of the reed valve while refrigerant is discharged through the refrigerant discharge hole; a keeper for limiting the degree of bending of the stopper caused by the reed valve, and a bolt settled at the keeper and connected with the stopper bent by the reed valve; and distance between the stopper and the bolt is controlled in accordance with the settling degree. It is preferable that a spring, for resisting against a bending deformation force of the stopper, is disposed between the stopper and the bolt.
According to the present invention, since a resisting force against the deformation of the reed valve is changed in accordance with change of discharge pressure of the refrigerant, discharging operation of the refrigerant is performed without any difficulties, and compressing efficiency is increased. Also, breakage of the reed valve can be prevented and noise is reduced because the shock of the reed valve is reduced.